If people do not believe that mathematics is simple, it is only because
they do not realize how complicated life is.

---John von Neumann

This quote is popular on web pages about von Neumann,
and about computing and mathematics generally. It is
apparently not from a published work of von Neumann's, but Franz L. Alt
recalls it as a remark made from the podium
by von Neumann as keynote speaker at the first national meeting of the
Association for Computing Machinery in 1947.
The exchange at that meeting is described at the end of Alt's brief article
"Archaeology of computers: Reminiscences, 1945--1947",
Communications of the ACM,
volume 15, issue 7, July 1972, special issue: Twenty-fifth anniversary of the
Association for Computing Machinery, p. 694.
Alt recalls that von Neumann "mentioned the 'new programming
method' for ENIAC and explained that its seemingly
small vocabulary was in fact ample: that future
computers, then in the design stage, would get along on
a dozen instruction types, and this was known to be
adequate for expressing all of mathematics....
Von Neumann went on to
say that one need not be surprised at this small number,
since about 1,000 words were known to be adequate for
most situations of real life, and mathematics was only
a small part of life, and a very simple part at that. This
caused some hilarity in the audience, which provoked
von Neumann to say: 'If people do not believe that
mathematics is simple, it is only because they do not
realize how complicated life is.'"